The present invention relates to storage circuits, semiconductor devices, and electronic apparatuses. In particular, the present invention relates to storage circuits that can readily read out stored data, semiconductor devices and electronic apparatuses equipped with the same, and methods for driving the same.
A conventional memory cell is disclosed in Japanese Laid-open Patent Application 64-66899 (Patent Document 1). The memory cell disclosed in the aforementioned Patent Document 1 is equipped with a static cell having two internal nodes, and a nonvolatile section having two ferroelectric capacitors. Then, by applying a voltage to the ferroelectric capacitors to the extent that the ferroelectric capacitors causes polarity inversion, a voltage on one of the internal nodes rises slightly higher than a voltage on the other of the internal nodes. By this, data is transferred from the nonvolatile section to the static cell.
[Patent Document 1] Japanese Laid-open Patent Application SHO 64-66899.
However, in the conventional memory cell described in the aforementioned Patent Document 1, for transferring data from the nonvolatile section to the static cell, it is necessary to pre-charge the bit line and further to apply the voltage to the ferroelectric capacitors. This causes a problem in that its operation becomes complex. Also, in the conventional memory cell described in the aforementioned Patent Document 1, although the voltage on one of the internal nodes becomes higher than the voltage on the other of the internal nodes, their difference is small. Therefore, there is a problem in that, if there are manufacturing variations in the threshold voltage of transistors composing the static cell, the static cell may malfunction.
Accordingly, it is an object of the present invention to provide storage circuits, semiconductor devices, and electronic apparatuses, which can solve the problems described above. This object can be achieved by combining the characteristics set forth in the independent claims in the scope of patent claims. Also, the dependent claims further define advantageous concrete examples of the present invention.